In recent years, from the point of view of environmental protection such as prevention of air pollution or the carbon dioxide discharge restraint and also from a point of view of utilization of the energy, hybrid vehicles and electric vehicles spread in large quantities. Large-capacity lithium ion batteries having characteristics such as high efficiency, the high output, a high energy density and the light weight etc . . . are carried to hybrid vehicles and electric vehicles.
The lithium ion battery is a large secondary battery having big electric capacity such as several tens of Ah (ampere-hour) and has a problem that in case of charging and driving considerable heat is generated depending on surrounding and becomes high temperature and may possibly cause a fire.
In addition, the lithium ion battery has a problem that when the battery is damaged in a traffic accident, a short circuit happens inside the battery and extreme huge electric current flows and causes a risk of a fire.
In addition, as for hybrid vehicles, they have problems that gasoline catches a fire from the fire occurred by the lithium ion battery as described above. And there is this risk to produce the large secondary fire.
As a method in order to solve this kind of problem, to install an electrical thermo-sensitive sensor in the lithium ion battery as extension of the technique known in the art and to install the outlet of a fire extinguisher operated by this thermo-sensitive sensor in a direction to the lithium ion battery, and a fire occurs, to sense a fire with the thermo-sensitive sensor and to operate a fire extinguisher by an electrical signal sent by the thermo-sensitive sensor and to extinguish the fire of the lithium ion battery are considered.
However, since various kinds of devices are installed in a crowd state inside of the engine room and there are almost no spaces, it is very difficult to install as the above described structure and also it is cost-consuming a lot, and this is a problem.